Hand planes have been used for hundreds of years to smooth the surface of wood. A hand plane works when a woodworker pushes or pulls the plane across the surface of the wood which allows the sharp blade or iron to shear off a thin layer of wood, thereby smoothing the wood surface.
FIG. 1 shows an exploded view of a prior art metal hand plane. The hand plane assembly 10 has a base 12, with a bottom surface or sole 14. The base 12 has an opening in the sole 14 which is called the throat 16. Attached to the base 12 is a rear handle or tote 18 and a front knob 19. A device called a frog 20 extends upward from the inside of the base 12. The frog 20 extends rearwardly from the throat 16 towards the tote 18, and holds the cutting blade, which is known as the iron 28. The user can turn the depth adjuster 22 which allows the iron 28 to extend farther through the throat 16. Adjustment of the iron 28 depth allows the iron 28 to engage a deeper or shallower cut in the wood being planed. The lateral adjuster 24 allows the user to adjust the iron 28 into a left or right position. This in turn, allows for deeper cuts on one side of the plane or the other. A bolt inserted near the center of the frog 20 is called the fulcrum stud 26. This stud 26 allows the iron 28 to be fastened securely to the frog 20, so as to make a secure, tight fit which holds the iron 28 in place during use.
In order for the iron 28 to be of use, it must be sharpened. The sharpened area on an iron 28 is called the bevel 29. Most prior art hand planes are designed in one of two ways. They either have the iron bevel up or bevel down in relation to the sole 14 of the plane. Typically planes that have a down bevel are similar to the design shown in the hand plane assembly 10. On the other hand, common bevel up irons are used in a different style of hand plane (not shown) which do not have the frog. Instead, the iron 28 lays on an inclined surface on the inside of the base 12 without the aid of the frog 20. This allows a bevel up iron 28 to lie at a much more reclined angle inside the base 12 of the plane, for use on wood with more difficult grain.
A cap iron 30 is used in conjunction with the iron 28 on bevel down type planes. The cap iron 30 is secured to the iron 28 by the use of a cap iron screw 36. This cap iron 30 acts has a lower chip breaker 38 which helps to curl the wood shavings cut by the iron 28 before they have a chance to split or tear away from the larger working piece of wood being planed. Overall, the chip breaker 38 contributes for much smoother cutting on the work surface of the wood. The iron 28 and the cap iron 30 when bolted together by the use of the cap iron screw 36 become one piece, which is held onto the frog 20 by the use of the lever cap 32. This lever cap has a lever 34 with a cam on the end which applies pressure against the cap iron 30 to hold the cap iron 30 and the iron 28 assembly in place on top of the frog 20. The cam on the bottom of the lever 34 causes the lever cap 32 to pivot around the fulcrum stud 26 and remain tight on the cap iron 30 and iron 28 assembly.
One of the primary problems with the conventional metal plane 10 is the ergonomics of the user's handgrip on the tote 18. The rearward angle and extension of the iron 28 into close proximity with the tote 18 interferes with the handgrip, particularly for people with large hands. Also, the large, cutting iron is difficult to grind and hone. The thin iron 28 is also subject to flex, because of the hollow ground bevel 29 and due to bedding of the iron 28 to the frog 20. Also, on smooth planes such as shown in FIG. 1, the physical space required for the inclined iron 28 and the rear tote 18 is approximately 7-10 inches, which leaves a relatively small amount of sole 14 in front of the iron 28 for registration on the wood, which decreases the accuracy of the planing process. Furthermore, the heel of the iron 28 must seat against the moveable frog 20, which moves the bedding of the iron 28 against the frog 20 up from the point of the heel, thereby decreasing the solidity of the bedding and resulting in chatter of the iron 28.
Another problem with this type prior art plane is that the pressure from the lever cap 32 or the clamping lever assembly 40 is applied to the cap iron behind the cutting edge of the iron 28. This allows the cutting edge of the iron 28 to vibrate and contributes to rough cuts. This creates opportunities for vibration and flex of the iron 28. This leads to chatter in thin cuts as the iron 28 loads and depends on the user to maintain a rigorous and forceful motion to keep the iron loaded during use. Every cutting edge, whether in wood or metal, needs a load (or bite) to work properly. With hand planes, the load occurs when the cutting edge first encounters the material to be cut. The edge of the blade or iron 28 deflects slightly and as long as there is significant forward motion of the plane, the iron 28 remains loaded and cuts the material.
FIG. 2 is a perspective view of a prior art wood block plane 40. The plane 40 includes a base 42 with a bottom sole 44 and a throat 46. A rear tote or handle 48 is attached to the top of the base 42. An elongated iron 50 is attached to a chip breaker 52 with a thumb screw or bolt (not shown). The iron 50 is retained in the throat 46 by a wedge 56. The iron 50 extends upwardly and rearwardly in close proximity to the tote 48, as seen in FIG. 2.
The wooden plane 40 also has problems due to the construction and arrangement of the throat 46 and iron 50. The typical 45°-50° angle of the iron 50 and the corresponding vertical or reverse angle of the throat 46 causes wear at the mouth of the throat, as the sole 44 wears away during use or is made true again, thereby progressively increasing the width of the throat opening. Also, the iron 50 must bed against the inclined throat opening cut into the wood block base 42. Since the wood is subject to warping, the iron may not seat properly. While the large iron 50 and the cap iron 52 provide rigidity, these elements are difficult to remove or adjust. Typically, the iron is hit with the hammer for both depth and lateral adjustment, which is far from accurate. Backing out or loosening of the iron 50 is normally accomplished by wrapping the base 42 either at the rear or on the top surface towards the front of the stock, which presents difficulties. Furthermore, due to the large size of the iron 50 and its 45°-50° angle, the top of iron 50 projects upwardly through the base stock 42 and interferes with the normal hand grip position on the tote 48. Some smooth planes dispense with the rear tote 48 or are configured as a horn plane smoother, as is common in European wooden planes. Most wooden planes 40 also use either a thick tapered iron 50 or a relatively thick straight iron. When the iron 50 is ground at a 25° angle for the bevel, the length of the ground bevel is relatively long. Therefore, the point from where the iron is bedded against the wood body at the heel of the iron, and actual cutting edge, is relatively long, thereby subjecting the cutting edge to flex and chatter when encountering obstinate grain. This problem is exacerbated when the bevel is hollow ground on small radius grinding wheels, as is common.
Accordingly, a primary objective of the present invention is the provision of an improved hand plane for planing wood.
Another objective of the present invention is the provision of a hand plane having a reverse angle frog.
A further objective of the present invention is the provision of a hand plane having interchangeable frogs.
A further objective of the present invention is the provision of a hand plane having a first frog for smooth planing and a second frog for scraper planing.
Still another objective of the present invention is the provision of a hand plane that functions as a chip breaker without having a separate chip breaking component.
Another objective of the present invention is the provision of a hand plane having cutting blades that are disposable or resharpenable.
Yet another objective of the present invention is the provision of an improved hand plane having a single means for both depth and lateral adjustment of the cutting blade.
A further objective of the present invention is the provision of a hand plane having a frog which is moveable fore and aft without the use of tools.
Yet another objective of the present invention is the provision of a hand plane having a solidly seated blade.
Still another objective of the present invention is the provision of a hand plane having a throat with a mouth that does not widen as the sole is worn down or trued.
A further objective of the present invention is the provision of an improved hand plane having a rear tote which can be gripped without interference.
Another objective of the present invention is the provision of an improved hand plane which is economical to manufacture, yet durable and effective in use.
These and other objectives will become apparent from the following description of the invention.